A vehicle door typically comprises an exterior panel that is formed of an outer, generally curved, exterior sheet of metal or plastic. The exterior panel conforms to the exterior surface of the body of the vehicle. An inner surface is formed on the panel by a metal sheet having edges peripherally secured to the outer sheet. The inner sheet is typically formed with a large central opening for access to a cavity provided between the sheets within the exterior door panel. A slot is formed at the upper edges of the two sheets for receiving a sheet of window glass. The glass sheet may be lowered into the cavity between the sheets for opening the window, or it may be raised upwardly for closing the window. Alternatively, the glass may be immovably fixed in the window opening with only its lower portion extending downwardly towards the cavity.
Various components are positioned within the cavity and may include a window mechanism for manually raising and lowering the window, a powered mechanism for raising and lowering the window by an electrical motor  and drive system, and locking mechanisms for the door, door handle components, side view mirror attachment and adjustment components, and the like.
A trim panel covers the cavity of the exterior panel is made of a sheet material that is of a size and shape to overlap and cover the interior surface of the exterior door panel. The trim panel may be formed of a thermoplastic material or a cloth type of material or a combination of both materials. Typically, the trim panel is molded or otherwise formed with a contoured or irregular surface that includes depressions, bosses, curved areas and the like. The peripheral edge of the trim panel is secured to the interior surface of the door panel by mechanical fasteners that can be disengaged so that the trim panel may be manually removed for providing access to the door components. Additionally, acoustic components such as stereo speakers can be mounted to the trim panel.
A water barrier or water shield is provided and is formed of a relatively thin flexible, water impervious, plastic sheet which is cut to the size and shape necessary for covering the respective surfaces. Traditionally, the sheet adheres to one or both of the adjacent door panels or trim panel surfaces. The water shield prevents dirt, dust and/or water from leaking into the vehicle through the vehicle door assembly.
Because conventional water shields are formed of large size, flexible or semi-rigid sheet plastic, sound generated by the acoustic components induces vibration of the water shield. This vibration results in resonant  frequencies that are disruptive to occupant comfort. Further, sound waves undesirably pass through the water shield can increase occupant discomfort.